Robotics Education & Competition Foundation
Online Challenges

Chain Tensioner


Entry ID #: 4527
Created: Fri, Jan 5, 2018 6:56 PM

Throughout many designs for VRC competitions I have consistently run into the problem of having too much or too little amount of tension in chain. Whether it’s chaining the drive together, powering a flywheel, or using a conveyer belt style intake, getting the right amount of tension in the chain drastically changes the quality of the design. To solve this tension problem, I’ve designed an adjustable roller bracket that will change the tension with more precision than simply changing the number of chain links.                 The roller bracket is designed to fit under a chain loop with too little tension so that it presses the chain outward taking up the extra slack in the chain. The extra slack in the chain changes depending on the distance between the sprockets so, to compensate for this, the rollers, within the brackets, are able to slide up and down at a 45-degree angle. The two rollers at a 45-degree angle, as opposed to a single roller that moves up and down at a 90-degree angle, keeps the bracket as low profile as possible.                 To design this bracket and roller, I first designed the roller by measuring the width of a standard vex high strength chain link and then I made the bracket by first making a base similar to vex C-channel with two slides at a 45-degree angle from the base for the rollers to be adjusted in. the rollers are designed to fit within the bracket and be attached using the standard 3/32” wide, 1 ¼” long bolt and a nylock. The bracket is designed to be attached to C-channel either along the side or the bottom of the bracket for any angle. Using Autodesk Inventor Professional 2017 I was able to create the bracket and the roller as separate parts and then assemble the bracket and rollers using the assemble feature of Inventor. Using premade vex components that currently exist I was able to assemble a common situation where tension in a chain would be a problem and then solve this problem by adding the roller bracket.                 This project taught me that it takes several iterations of designs to come up with a solution to a problem such as this. I first design a bracket that had three stationary rollers before realizing that it only needed two and that they needed to be able to adjust vertical positions to account for differences in chain slack. It showed me that using CAD software makes designing a three-dimensional model much more efficient than other methods and that testing a design can be done without having the physical components of the design. This type of software can help me assemble different designs for a robot before building it which is more efficient as it takes less time and gives me information on the needed length of C-channel or other structural components so that I only need cut it once. In future careers in engineering this software will be very advantages in designing components for projects and testing those components. As I hope to pursue a career in mechanical engineering, it helps me to know how to use software such as this.